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991.
将棒状纳米凹凸棒石黏土加入到α-环糊精(α-CD)和PEO-b-PPO-b-PEO(EPE)嵌段聚合物形成的超分子水凝胶中,构建了一种新型复合水凝胶.用X射线衍射仪(XRD),傅立叶红外光谱仪(FT-IR),扫描电镜(SEM)和流变测试等方法表征了该复合水凝胶的结构和性能.实验结果显示:加入适量纳米凹土不会破坏α-CD/EPE聚轮烷的聚集结晶特性;当复合水凝胶中纳米凹土的质量分数小于2.5%时,适量的纳米凹土能改善水凝胶海绵状结构的连续性,增加海绵状结构的壁厚和孔隙率;随着纳米凹土含量的增加,复合水凝胶的凝胶化时间减少且刚性和机械强度得到了提高. 相似文献
992.
在温和条件下手性薄荷酮腙(1)与NO在痕量O2存在下发生偶氮-硝化反应,高选择性的生成α-硝基偶氮化合物. 通过DEPT谱、1D NOE差谱和1H- 1H COSY,HSQC等2D NMR技术对目标化合物2(2,4-二硝基苯基-1-硝基-(2-异丙基-5-甲基)环己基-二氮烯)的1H,13C NMR 谱的信号进行了全归属和较详细的解析,确定了目标化合物2的结构. 相似文献
993.
994.
W.-L. Feng 《Optik》2009,120(14):696-2699
In this paper, the optical absorption spectra of Yb3+ in the α-Al2O3 crystal are reasonably explained by using the superposition model and local lattice structure analysis. Based on these studies, we find that the local geometrical structure around the Yb3+ ions possesses an elongated trigonal distortion above the O2−-triangle and a compressed trigonal distortion in the lower one. 相似文献
995.
996.
A new compound N-naphthyl-2-deoxy-α-D-ribopyranosylamine was synthesized and structurally determined. It crystallizes in the orthorhombic system, space group P212121 with a = 8.361(2), b = 12.432(3), c = 12.791(4) A^°, Z= 4, V= 1329.6(6) A^°^3, Dc= 1.295 g/cm^3, F(000) = 552, Cl5H17NO3 and Mr= 259.30. All the active hydrogen atoms are involved in the formation of hydrogen bonds in the molecule. 相似文献
997.
α-Rhombohedral (α-rh) boron, which is the most stable of boron's polymorphs at low temperatures, has p-type semiconductive properties. There have been some attempts to dope the interstitial sites with alkali atoms to create metallic or n-type semiconductive α-rh boron, but this has yet to be achieved. In a previous work, we proposed the codoping of α-rh boron with Li and P or As, and revealed from first principles calculations that B12PLi and B12AsLi could be synthesized and become narrow-gap semiconductors. The band structure suggested that the mobility of electrons might be greater than that of holes. In this paper, based on these prospective results, we selected a new combination of dopants, Li and O, and theoretically studied such compounds as B12OLi and B12O2Li. The results showed that both of these materials are metallic, while the reaction energies of the Li insertion into B12O and B12O2 are lower (more unstable) than with B12PLi and B12AsLi. It was proved that the differences in the electronic structures are caused by the dangling bonds of the dopant atoms, O, P and As. 相似文献
998.
Pengpeng Zhang Xiaoqing Shen Aixiang Tian Yuan Chen 《Journal of solid state chemistry》2009,182(12):3399-157
A new compound based on polyoxometalates, [Cu(bbi)]5H[H2W12O40] (1) (bbi=1,1′-(1,4-butanediyl)bis(imidazole)), has been hydrothermally synthesized and characterized by elemental analyses, IR spectroscopy, thermogravimetric analyses, and single X-ray diffraction. Compound 1 shows a twofold 3D+3D topology, and it represents the first interpenetrating network based on the isopolytungstate. The electrochemical property of compound 1 modified carbon paste electrode (1−CPE) was investigated in 1 M H2SO4 solution, and the results indicate that 1−CPE exhibits the electrocatalytic activity toward the reduction of bromate and nitrite. Further, the non-isothermal kinetics of the thermal decomposition of compound 1 provides the dynamic parameters E (activation energy) and A (pre-exponential factor) for the pyrolytic reaction of the organic ligands. 相似文献
999.
α-Trifluoromethyl-β-aryl enamines were successfully used as synthetic equivalents of benzyltrifluoromethyl ketones in both the Fischer indole synthesis and the Pictet-Spengler reaction. Accordingly, 2-trifluoromethyl indoles and a variety of trifluoromethylated 4,5,6,7-terahydro-1H-pyridines including carbolines were synthesized in moderate to good yields. 相似文献
1000.
《Tetrahedron》2009,65(25):4908-2413
3-Butyl-3-amino-1H,3H-quinoline-2,4-diones react with isothiocyanates to give novel 3a-butyl-9b-hydroxy-2-thioxo-1,2,3,3a,5,9b-hexahydro-imidazo[4,5-c]quinolin-2-ones in high yields. These compounds rearrange in boiling acetic acid or concd hydrochloric acid to give (E)- and/or (Z)-4-butylidene-2-thioxo-1′H-spiro[imidazoline-5,3′-indole]-2,2′-diones. All compounds were characterized by their 1H, 13C, IR and MS spectra, and some of them also by 15N NMR. The structure of one compound was investigated by single-crystal X-ray diffraction. 相似文献